Lapping machine



Nov. 21, 1950 DICKINSON 2,530,424

LAPPING MACHINE Filed July 31, 1947 s Sheets-Sheet 1 M Ma vNToFa.

E. DICKINSON LAPPING MACHINE Nov. 21, 1950 3 Sheets-Sheet 2 Filed July 31, 1947 mm hm INVENTOR.

ATTORNEY.

mm mm um Nov. 21, 1950 E. DICKINSON I 2,530,424

' LAPPING MACHINE Filed July 51, 1947 3 Shee ts-Sheet :5

INVENTOR ATTORNEY.

Patented Nov. 21, 1950 signer, by mesne assignments; to A. C. Wickman, Limited, Coventry, England, a British company Application July 31, 1947; Serial No. 765,024 In Great Britain December 21-, 19455- 8 Claims. 1-.

This invention relates to lapping machines of the kind in. which a. reciprocable lapping rod or'tool; is; provided. to operate through a hole in the rotating. work. When in use the lapping tool is provided. with abrasive material.

In lapping. machineshitherto proposed for lapping openings of venturi. shape as in wire drawing dies the lapping wire or. tool is.- given the required bowed. form by: placing supports through which it is guided out. of line with the opening. in the work, the resultant thrust of the work producing. the required bowed form. In such an arrangement the shape-of the bowedform depends upon the lateral pressure between toolian'd work and thus the. shape is necessarily effected if,.to.- alter the rated removal of metal from the worl the: laterali pressure is eased or increased somewhat.

In another arrangement inwhich the degree of bowingt'need not depend entirely upon thelateral thrust of: the work, supports for the lapping tool arranged onieither side-ofathe work serve to. clamp portions of the; lapping tool-so that it may take up a bowed formevenrin. the absence of the work; the supports however are moved bodily with the lapping toolv sothat: in the course of reciprocation oftoolv and supports engagement of the work by the lappingxtoolnecessarily modifi'es the shape of the. bowed form;

One object of the.presentinvention is to provide Another object of the present invention is to provide a lapping machine for lapping the walls of openings which. are or which are required to be of barrel shape, or for'la'pp-ing" the walls of other openings towhich similar treatment isrequiredto be applied althoughznotnecessarily continued. to. the. stage: at whiohihe; opening becomes barrel shaped. For. instancearprimary object of the invention is to providezaimachine for finishing the: surfaces: of cylindrical holes particularly in very hard material: more accurately than hitherto. 1

The essential feature of the present invention isthat the bending: means acting: upon.- thelapping tool to bendit into. bowed formiactsrindependently of the-lateralthrustof theworkzup'on the lapping tool. andthe bendingmeansiarestationary relative to: the work in.- the' direction: of reciprocation ofrtheilappingtool so tha'tthe shape of the: bowed portion is: not modified'iin the reciprocation of. the lapping tool.

The invention is illustrated in the-accompanying: drawings, wherein:

Figure 1 is a View in side elevation.

Figure 2 is a view in plan.

Figure 3 is a section onthe line 3-3 of. Fig-.- ure 2.

Figure 4 is a section on the line 4-4 of Figure 1*.

Figure 5 is a section on the line 5--5 of Fig-- ure 1.

Figure 6 is a section on the line 66 of- Figure 5.

Figure '7 isa view in end elevation showinganother method of mounting the rollers" in. an adijustable manner, and

Figure 8 is a view inside elevation illustrating a modification.

Figures!) and IO-are plan views showing alternative-methods ofimparting thenecessarybowing tothelapping'tool. The bowing has been greatly exaggerated for the-sake'of clarity.

Figures 5, 6; 7, Sand 10 are'drawn to-alarger scale than Figures 1 to 4and"8.

In the construction illustrated the machine comprises a base plate [8, which may be formed as a casting and which may hav'ea downwardlydirected peripheral flange H and a numbero'f downwardly projecting ribs on its underside extending from and connecting the peripheral lips at opposite sides.

At one end the base plateis provided with a portion [2 which is wider than the remainder of' the base plate, and adjustably mounted on this portion is a supporting plate l3 upon which is mounted an electric motor or other power unit 141 The plate is supporting the power unit'may be attached to. the base plate by means of studs l5 which pass-through slots [6 in the supporting plate, the slots being parallel tothe length of the base plate so that the position of the'power unit can be adjusted on the base plate.

The base plate it isfurther provided: with an upwardly-projecting rib l-l' arranged. longitudinally, and the underside of the-supporting platefor the power unit is provided with a channel whichengages over this rib.

The motor or power unit has a driving. shaft which projects-from one end and extends over the said rib, and on this driving shaft is mounted a driving pulley it. If desired reducingage'aringmay be interposed between the driving-pulley andthe driving shaft of the power unit.

Mounted at opposite'sides ofthenarrower part of" the base plate are two brackets [9, one at ping device.

a each side. These brackets are bolted at 20 to the sides of the base plate, and they extend upwardly. At the top they are provided with bushes 2! which form supporting guides for the reciprocating lapping tool 22 the internal bearing paces of the bushes providing support for the lapping tool in a direction substantially radial with respect to the wall portion of the opening in the work which as will appear from the subsequent description the lapping tool will engage. This tool may take the form of a cylindrical rod, and if it is to be hand-operated, at one end on the outer side of one of the supporting bushes it is provided with a knob 23 by which it may be operated.

Instead of operating the lapping tool by hand, it may be mechanically operated, in which case it is reciprocated in the two bushes, and it may be given a periodical turning movement on its own axis.

Mounted concentrically with the bushes which support the lapping tool we provide on the base plate, one on either side of the longitudinal rib thereon, two bearing housings 25. Each of these bearing housings is adapted to receive a ball or roller bearing E i, and these bearings may be retained in position in the housings by inner and outer plates 25, 22 secured to opposite sides of the housings, these plates engaging partially over the ends of the bearings.

The work holder takes the form of a pulley 28 mounted in these bearings, the pulley having a portion between the bearings, which pulley may have a grooved periphery 29 upon which operates a driving belt 38 engaging the pulley l3 driven by the power unit.

The pulley 28 forming the work holder is provided with flanges 31 on either side of its central belt-engaging portion, and these flanges engage the inner members of the ball or roller bearings 24 and are supported thereby. The flanges 3i are shouldered at 32 so that the bearings are engaged each at one end, as well as at the inner periphery.

The central part 3 of the pulley forming the work holder is provided with a cylindrical opening in which is mounted a bush 33 which is split longitudinally and forms a work-grip- This central part 3% of the pulley forming the work holder is provided with a plurality of openings 35 spaced around the centre, and in two or more of these openings are situated radial set screws 36 adapted to act upon the split bush 33 for gripping the work which is mounted within the bush.

The bearing housings 25 at the end remote 'from the power unit are provided with flat surfaces disposed at right angles to the top of the base plate, and secured to these surfaces by suitable means are two guide members 31 extending horizontally and adapted to form a fixed guide for a sliding block 38.

These guide members 3? have portions 39 of channel form in which portions of the sliding block 38 engage. The guide members are provided with flanges as which are bolted to the sides of the bearing housings, and their channel-section guide portions extend horizontally one above the other in spaced relationship, the open sides of the channels being directed towards each other.

The sliding block as is provided with a portion 42 which extends horizontally between the edges of the channel-section guides and is further provided with longitudinal ribs as on the centre line above and below which engage in the channels of the guide members.

The main part 42 of the sliding block extends horizontally and transversely between the guide members, and the outer ends of these horizontally and transversely extending portions are formed as channels 44 in which are secured a pair of arms 45 extending laterally towards the lapping tool and having their end portions 46 cranked inwardly and carrying pins 41 upon which are mounted flanged rollers 48 which engage one side of the lapping tool on either side of the split bush forming the work holder, the flange of each roller including an axially directed tool carrying face portion.

Each roller 48 and associated bracket 19 provided with a bush 21 forming a journal bearing for the lapping tool combined to define a guide path for the lapping tool. This guide path is defined both in the horizontal and the vertical plane since the bush encircles the lapping tool at one end and since at the other end of the guide path the roller is provided with a flange having an axially directed tool carrying face portion which locates the lapping tool in the vertical plane whilst location in the horizontal plane is achieved by the radially directed circumferential face of the roller. As shown in Figure 6 the axial and radial locating faces of the roller may, in fact, merge into one another by virtue of the peripheral groove of part circular cross section provided in the circumferential face of the roller and in which the lapping tool 22 is seated.

In the modification shown in Figure '7, each of the rollers 48 is closed at the end 69 andis supported on the pin 41 mounted in the arm 46. At its lower end each roller 48 is provided with a flange H3 engaging beneath the lapping tool, and in order to make provision for different diameters of lapping tool, the pin 41 may be adjusted vertically by means of a screw 1 I having a flange 12 engaging in a groove in the pin 41.

e screw H screws into the arm 46.

The roller 48 may be mounted on a bush or a roller or ball bearing 13. In order to prevent the roller 48 from moving upwardly and leaving the pin 41, we may provide a bracket 14 on the arm 45 having a portion extending above the roller 48 and an adjustable screw 5 for engaging the top of the roller.

The arms 45 carrying these flanged pressure rollers are located in channels at the outer ends of the sliding block 38, and are fixed therein by separate clamping plates 49, 50, respectively engaging the sides and ends of the said arms.

The arms 45 may receive additional support at the position where the arm 45 joins the arm 46 and such support may be received from an adjustable screw 16 screwing into a pillar TI, these pillars being mounted upon the bases of the bearing housings 25.

Further, as shown in Figure 8, one or both of the arms 45 may be adjustable in an endwise direction, and for this purpose the end of the arm compression spring 5|, and this spring is placed upon a central pin 52'extending through the assecae 51 sliding block and secured: to. it by a nut- 531cm gaging. a washer at one side of the. slidingblock, the. pin having.- a flange 54 engaging in the end of a recess 55 in the opposite side of the sliding block.

Theendsor the two guide members3fl in which the. sliding block operates are connected by a crossrplate 55 in. which is a'threaded hole, into which screws an. abutment formed asa cupshaped. box 51 for one end. of the compression spring 51'. This boxcan be adjusted by turn.- ing. it on its own axis so as tovary the pressure of the spring. One end: of the spring is housed in this box and engages theend ofthe box, while the. opposite end of thespring engages the flange 54: on, the pin 52 which isattached: to the sliding. block, the. arrangement being such that the spring. presses the sliding. block towards the lapping tooland causes the flanged rollers carried by the-two arms to-press against the side of' the lapping tool which is. remote. from the power unit.

It will be apparent that the lapping tool is thus bent into bowed formation by the pressure of the rollers, and that theflanges'on the rollers provide a toolsupporting face whichresists thrust exerted upon the lapping-toolin a direction tangential to the wall: portion of the-opening in the work engaged bythe lappingtool.

As seen more especially in Figureitis preferred to place therollers close to the work so that the flanges of the rollers give suchtangential support to the lapping tool close to the ends of the portion of= the tool within the work.

This spring pressure acting upon the sliding block operates against a wedge-deviceconstituting an adjustable. stop which isformed as a U-shaped member 58, the limbs of which slide vertically against suitable facings 5-9 on the flanges of theguidemembers 37. The opposite sides of the vertical limbs. 66 of the adjustable stop 58- are formed as'inclines and engage correspondingly inclined: surfaces 6 I provided on the sliding block 38;

At the top the two limbs of the adjustable stop are integrally connected andareprovided with a horizontally-extending flange-62-in which is mounted a nut- 63 having flanges engaging opposite sides of the flange 6 2 of the adjustable stop. This nut engages a vertical screw 64 carried by the upper guide member '31, and'the arrangement is such that when the nutais turned the adjustable stop, member 53 is. adjusted either upwardly or downwardly so as to effect an alteration of the extent to which the spring pressure can bend the-lapping tool.

In order that finished work may be takenout and fresh work inserted, means are provided for moving the arms idcarrying the pressurerollers in anendwise. direction tobring them away from thelapping toolsothat the lapping tool'can be withdrawnfromthework and the work'removed and a fresh. pieceof work inserted.

To provide; for-this movement of the pressure rollers and the arms carrying them, I mount upon the connecting plate ttsecured tothe ends .qfjthe two guide members-a cam plate 65 having a face cam 66 at its end adapted to be engaged by a cross peg 67 extending through the pin 52, the arrangement being such that when the pin is turned on its own axis it is moved in an endwise direction through a suitable distance and retained in its new position. Movement of the pin in this way will move the sliding block so as to bring the pressure rollers away from the side of 6 the: lapping tool. The. in provided with. alever handle 581by which it. may befturned.

In the alternative; construction illustrated in Figure 9 the bowing of the lappingtoolZ-Z is obtained by mounting the supports 21 for said lapping tool s9. that their axes are. not parallel but form. an. obtuse angle. Each support. 2. lis mount.- ed. on. a circular bed 182 said bed being itself pivotally mounted on the, top of the bracket i9 said: bracketbeing suitably modified for this-pure pose. The bed 181 has a pairof upstanding arms is which. are adapted to.- partially embrace and to. secure the supports: 2 l: and; a ing 8!]: extends sideways. from said bed: and: this. lug 8.0 carries an arcuate slots-1.. Abolt. 82 passes through this slot 8:! and; engages. in a tapped. hole formed. in the. bracket. 1 9. so. that the bed; 118- and the. support 2t; may. be clamped in a plurality of, differentpositions. The bedl8-is. provided with: a. pointer Stuadaptedtooperatc over a. suitable scalemarked on. the bracket 89,: to indicate the degree of bows ing oitthe lapping tool for a. given. setting; of the bed.

In Figure is illustrateda still further method of. obtaining the bowing of the lapping tool 1 leverbeing mounted: at 88' for pivotal movement about a. vertical axis. and the end of: said lever having a. V shaped-recesscut therein whereby it may, be engaged byahea'daBQ'said1headbeingattachedtoone of the arms. dfixwhereby equal pressure, from opposite directions, may be-exerted on the tool 22 by the rollers 48.

What I claim then is:

1. A lapping machine comprising a holderv for the work, a reciprocable lapping tool adapted to extend through an opening in the work, means for rotating the work holder and the tool relatively with the tool engaging successively. circumierentially spaced wall portions oftheopening in the work, a; pair ofxarms extending lat.- erally towards. the lapping tool; a. supporting structure for said arms, said supporting-structure comprising a fixed guide arrangedisubstantially at right angles to; the lapping tool, a slida l bl ckmountediin sa d. guide, said arms-bein carried by said block a spring acting on said block and; pressing ittowardsthe lapping tool, awedge device operatingpbetweena. fixed surface of said block and: adapted'to limit the movement 7 of the. block. under the influence of. the spring,

said armsbeing spacedapart; one on each side'of thework holder; andhaving cranked end. port-ions carrying rollers adapted. to apply. to the lapping, tool; a lateral thrust radial. supporting elements for the tool positioned on each side of thework, said elements including tool: supporting;abutm e nt portions facing in adirection substantia rradialwithirespectto the wall portion of the opening which the tool is adapted to engage and counter to the direction of said lateral extend through an opening in the work, means for rotating the work holder and the tool relatively with the tool engaging successively circumferentially spaced wall portions of the opening in the work, a pair of arms extending laterally towards the lapping tool, a supporting structure for said arms, said supporting structure compris ing a fixed guide arranged substantially at right angles to the lapping tool, a slidable block mounted in said guide, said arms being carried by said block, a pin mounted on said block and arranged parallel to the guide, a plate secured to the supporting structure at the end of the guide remote from the tool, said plate having an opening through which the pin extends, a flange on said pin, a spring disposed on said pin and acting between said flange and abutment means secured to said plate, said spring pressing said pin and block towards the lapping-tool, a cross peg on the portion of the pin projecting from said plate,

a cam plate carried by said plate and co-operating with said cross peg in the rotation of the pin in one direction to impart endwise movement to the pin and block away from the lapping tool, a wedge device operating between a fixed surface and said block and adapted to limit the movement of the block under the influence of the spring, said arms being spaced apart one on each side of the work holder and having cranked end portions carrying rollers adapted to apply to the lapping tool a lateral thrust, radial supporting elements for the, tool positioned on each side of the work, said elements including tool supporting abutment portions facing in a direction substantially radial with respect to the wall portion oi the opening which the tool is adapted to engage and counter to the direction of said lateral thrust of the rollers upon the tool, said rollers engaging the tool to apply said lateral thrust at positions intermediate said radial supporting elements and the work.

3. In a lapping machine of the kind specified, a rotary workholder, and guide structures positioned on each side of the workholder, each of said guide structures comprising a fixed journal bearing for a lapping tool, and a roller positioned intermediate said bearing and the Workholder and supported adjustably in relation to said bearing in a direction transverse to the axis of said bearing, said roller being provided with means for preventing movement of a lapping tool across its circumferential face.

4. In a lapping machine of the kind specified, a rotary workholder, and guide structures positioned on each side of the workholder, each of said guide structures comprising a fixed journal bearing for a lapping tool, and a roller positioned intermediate said bearing and the workholder and supported adjustably in relation to said bearing in a direction transverse to the axis of said bearing and the axis of the roller, said roller being provided With means for preventing movement of a lapping tool across its circumferential face.

5. In a lapping machine of the kind specified, a rotary workholder, and guide structures positioned on each side of the workholder, each of said'guide structures comprising a fixed journal bearing for a lapping tool, and a roller positioned intermediate said bearing and the workholder and closely adjacent to the latter, said roller being supported adjustably in relation to said bearing in a direction transverse to the axis of said bearing, and said roller being provided with means for preventing movement of a lapping tool across its circumferential face.

6. In a lapping machine of the kind specified, a rotary workholder and guide structures positioned on each side of the workholder, each of said guide structures comprising a fixed journal bearing for a lapping tool and a roller positioned intermediate said bearing and the workholder and supported on an arm having a roller supporting inner end portion cranked inwardly towards the side face of the workholder, said roller being supported adjustably in relation to said bearing in a direction transverse to the axis of said hearing and said roller being provided with means for preventing movement of a lapping tool across its circumferential face.

7. In a lapping machine of the kind specified, a rotary workholder, and guide structures positioned on each side of the workholder, each of said guide structures comprising a fixed journal bearing for a lapping tool, and a roller positioned intermediate said bearing and the workholder and supported adjustably in relation to said bearing in a direction transverse to the axis of said bearing and the axis of the roller, said roller be ing provided with a lapping tool supporting flange co-planar with the axis of the workholder.

8. In a lapping machine of the kind specified, a rotary workhoider, and guide structures positioned on each side of the workholder, each of said guide structures comprising a fixed journal bearing for a lapping tool, and a roller positioned intermediate said bearing and the workholder and supported adjustably in relation to said bearing in a direction transverse to the axis of said bearing and the axis of the roller, said roller being provided with a groove in its circumferential face, said groove being of part-circular crosssectional shape, and co-planar with the axis of the Workholder.

ERNEST DICKINSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 534,767 Sponsel Feb. 26, 1895 1,428,209 Blount Sept. 5, 1922 1,714,869 Haddow May 28, 1929 1,826,347 Haddow Oct. 6, 1931 1,880,729 Blount Oct. 4, 1932 1,885,178 Bsteh Nov. 1, 1932 1,912,016 Sittner May 30, 1933 2,372,722 Heim Apr. 3, 1945 FOREIGN PATENTS Number Country Date 547,572 Great Britain Sept. 2, 1942 

